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Re: i386 RTX_COST tweeks take 2

To: Jan Hubicka <jh at suse dot cz>
Subject: Re: i386 RTX_COST tweeks take 2
From: Richard Henderson <rth at redhat dot com>
Date: Wed, 7 Nov 2001 11:50:47 -0800
Cc: Andi Kleen <ak at suse dot de>, gcc-patches at gcc dot gnu dot org, gcc at gcc dot gnu dot org
References: <20011103174136.A23260@atrey.karlin.mff.cuni.cz.suse.lists.egcs> <Pine.LNX.4.33L2.0111050649160.30025-100000@kevin.inet.suse.lists.egcs> <20011105154541.A9715@atrey.karlin.mff.cuni.cz.suse.lists.egcs> <p73pu6wyb1w.fsf@amdsim2.suse.de> <20011106175612.B8917@atrey.karlin.mff.cuni.cz> <20011106235244.I29844@redhat.com> <20011107133657.B20978@atrey.karlin.mff.cuni.cz>

On Wed, Nov 07, 2001 at 01:36:57PM +0100, Jan Hubicka wrote:
> http://gcc.gnu.org/ml/gcc-patches/2001-08/msg01491.html
> 
> It saves one extra copy after expanded multiplies.

Why can't we repair the damage with globals?  Why wouldn't 
fixing this be any different than if the code used a local
variable as an intermediate?

While preserve_subexpressions_p may not be the best heuristic,
not using it consistently is confusing.

r~

Follow-Ups:
- Re: i386 RTX_COST tweeks take 2
  - From: Jan Hubicka

References:
- Re: Performance of Integer Multiplication on PIII
  - From: Andi Kleen
- i386 RTX_COST tweeks take 2
  - From: Jan Hubicka
- Re: i386 RTX_COST tweeks take 2
  - From: Richard Henderson
- Re: i386 RTX_COST tweeks take 2
  - From: Jan Hubicka

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